Cephalosporin derivatives

Abstract

New cephalosporin derivatives of the formula: ##STR1## wherein one of A and A 1 represents oxygen or sulphur and the other represents sulphur, R 1 represents hydrogen, acetoxy, (5-methyl-1,3,4-thiadiazol-2-yl)thio or (1-methyl-1,2,3,4-tetrazol-5-yl)thio and R 2 represents carboxy, or R 1 represents a pyridinio radical and R 2 represents the carboxylate ion, are therapeutically useful compounds possessing antibacterial properties.

We claim: 
     
       1. A cephalosporin derivative of the formula: ##STR5## wherein one of A and A 1  represents oxygen or sulphur and the other represents sulphur, R 1  represents hydrogen, acetoxy, (5-methyl-1,3,4-thiadiazol-2-y )thio or (1-methyl-1,2,3,4-tetrazol-5-yl )thio and R 2  represents carboxy, or R 1  represents a pyridinio radical and R 2  represents the carboxylate ion, and when R 2  represents the carboxy radical pharmaceutically-acceptable salts thereof. 
     
     
       2. A cephalosporin derivative according to claim 1 wherein A and A 1  each represent sulphur. 
     
     
       3. The cephalosporin derivative according to claim 1 which is 3-acetoxymethyl-2-carboxy-7-[(5,6-dihydro-1,4-dithiin-2-yl ) acetamido]-8-oxo-5-thia-1-aza-bicyclo-[4,2,0]oct-2-ene and pharmaceutically-acceptable salts thereof. 
     
     
       4. The cephalosporin derivative according to claim 1 which is 2-carboxy-7-[(5,6-dihydro-1,4-dithiin-2- yl )acetamido]-3-methyl-8-oxo-5-thia-1-aza-bicyclo[4,2,0]-oct-2-ene and pharmaceutically-acceptable salts thereof. 
     
     
       5. The cephalosporin derivative according to claim 1 which is 2-carboxy-7-[(5,6-dihydro-1,4-dithiin-2-yl )acetamido]-3-[(1-methyl-1,2,3,4-tetrazol-5-yl )-thiomethyl]-8-oxo-5-thia-1-aza-bicyclo]4,2,0]oct-2-ene and pharmaceutically-acceptable salts thereof. 
     
     
       6. The cephalosporin derivative according to claim 1 which is 3-acetoxymethyl-2-carboxy-7-[(5,6-dihydro-1,4-oxathiin-2-yl )acetamido]-8-oxo-5-thia-1-aza-bicyclo-[4,2,0]oct-2-ene and pharmaceutically-acceptable salts thereof. 
     
     
       7. The cephalosporin derivative according to claim 1 which is 3-acetoxymethyl-2-carboxy-7-[(5,6-dihydro-1,4-oxathiin-3-yl )acetamido]-8-oxo-5-thia-1-aza-bicyclo[4,2,0]oct-2-ene and pharmaceutically-acceptable salts thereof. 
     
     
       8. The cephalosporin derivative according to claim 1 which is 2-carboxy-7-[(5,6-dihydro-1,4-dithiin-2-yl ) acetamido]-3-[(5-methyl-1,3,4-thiadiazol-2-yl )thiomethyl]-8-oxo-5-thia-1-aza-bicyclo[4,2,0]oct-2-ene and pharmaceutically-acceptable salts thereof. 
     
     
       9. The cephalosporin derivative according to claim 1 which is 2-carboxylato-7-[(5,6-dihydro-1,4-dithiin-2-yl ) acetamido]-8-oxo-3-(1-pyridinio-methyl)-5-thia-1-aza-bicyclo[4,2,0]oct-2-ene. 
     
     
       10. The cephalosporin derivative according to claim 1 which is 2-carboxy-7-[(5,6-dihydro-1,4-oxathiin-2-yl )acetamido[-3-[(5-methyl-1,3,4-thiadiazol-2-yl )-thiomethyl]-8-oxo-5-thia-1-aza-bicyclo[4,2,0[oct-2-ene and pharmaceutically-acceptable salts thereof. 
     
     
       11. The cephalosporin derivative according to claim 1 which is 2-carboxy-7-[(5,6-dihydro-1,4-oxathiin-2-yl )acetamido]-3-[(1-methyl-1,2,3,4-tetrazol-5-yl )thiomethyl]-8-oxo-5-thia-1-aza-bicyclo[4,2,0]oct-2-ene and pharmaceutically-acceptable salts thereof. 
     
     
       12. Alkali metal, alkaline earth metal, ammonium and pharmaceutically-acceptable amine salts of a cephalosporin derivative as claimed in claim 1 wherein R 2  represents the carboxy radical.